Composite glare overlayed by alpha transparency of other material?
Solution 1:

You might want to switch the blending mode from 'add to 'screen'



Solution 2:

Instread of a mix node you can use an 'alpha over'. to my experience this works better for more complex overlays with multiple colours. make sure you add the alpha channel to the 'alpha over' node or it won't work
(in your case you would take the alpha from one of the 'ID masks', not the alpha from the image)